It's kind of hard to tell since he's a dark colored betta (very handsome btw!), but I didn't see any sign of fin rot or redness in that video. I would say he either torn his fins like you said or he may be a finbiter. I have 2 former biters (for the most part at least) & when they actively bite their fins start to look like that. Based on what I see, I wouldn't worry about fin rot.

Nope, no fin rot IMO. He seems like a very healthy betta :) As long as you keep his tank clean, you should never have to worry about fin rot. Just remember to keep an eye on his tail in case he gets some sort of infection from the tears, which is very unlikely as long as he gets weekly changes. Very pretty BTW. ;)